\chapter{排列，组合，二项式定理}

\section{排列与组合}

\input{units/ds3-ch2-1}
\input{units/ds3-ch2-2}
\input{units/ds3-ch2-3}
\input{units/ds3-xiti-3}

\vspace{2em}
\input{units/ds3-ch2-4}
\input{units/ds3-ch2-5}
\input{units/ds3-ch2-6}
\input{units/ds3-xiti-4}

\vspace{2em}
\section{二项式定理}

\input{units/ds3-ch2-7}
\input{units/ds3-ch2-8}
\input{units/ds3-xiti-5}

\vspace{2em}
\input{units/ds3-ch2-xiaojie}

\nonumsection{复习参考题二}
\input{units/ds3-ch2-fuxi-A.tex}
\input{units/ds3-ch2-fuxi-B.tex}

